-80.9% is the change from 670 to 128
Calculation steps:
[( 128 - 670 ) ÷ 670] x 100 = -80.9%
Formula
Percentage change = [(128 - 670) / 670] x 100
Subtract the new number by the original number
128 - 670 = -542
-542 ÷ 670 = -0.808955223880597
-0.808955223880597 x 100 = -80.9%